1. Field of the Invention
The invention disclosed and taught herein relates generally to a method and system of locating and/or tracing along pre-selected anatomical features that includes processing digital images of the general region of the structures to locate the specific features, mathematically determining a distance between such features, comparing the determined distance to normative data, and reporting the results. More specifically, the invention can be used to determine a distance between anatomical features from analyzed subcutaneous images such as computerized tomography (CT) scans, comparing the distance to normative data for possible ligament damage, and reporting the results.
2. Description of the Related Art
FIG. 1 is a prior art drawing of an exemplary skull of a human showing anatomical regions. FIG. 2 is a prior art drawing of an inferior view of the bottom of the skull showing the basion and foramen magnum. FIG. 3 is a prior art perspective drawing of a first vertebra (“atlas”) located above the second vertebra (“axis”) with a dens and a vertebral foramen. FIG. 4 is a prior art exemplary CT scanned image in a sagittal plane of a typical skull showing anterior and posterior portions of the skull and the basion on the skull located above the dens on the axis. The figures will be described in conjunction with each other. The reference orientations and directions shown in the figures are based on customary medical orientations for imaging and include the following positions relative to a chosen datum, for example, the skull as shown in FIG. 1: a superior position 6 is upwardly disposed, an inferior position 8 is downwardly disposed, an anterior position 10 is forwardly disposed, and a posterior position 12 is rearwardly disposed. For purposes herein, the following axes are defined. The X-axis is oriented horizontally in the images (toward the right image side) and corresponds to the posterior anatomical direction. The Y-axis is oriented vertically in the images (toward the top of the image) and corresponds to the superior anatomical direction. These axis definitions are consistent with common use in current medical practice. Expanding these definitions to three dimensions, the Z-axis is oriented perpendicular to the sagittal (X-Y) plane of the images (and pointing outward from the image plane), and corresponds to a lateral, leftward anatomical direction. A Z-X plane is shown in FIG. 5.
The skull 2 has a region known as the occipital region 4 that extends from the back of the skull to an underneath position adjacent the mandible. An occipito-cervical complex (OCC) is defined as the region extending from below occipital region 4 (FIGS. 1 and 2) to the second cervical interspace 29 (FIG. 3) that is between first and second vertebra of the neck and thus includes the region of the vertebra that connects to the skull. A first vertebra 18 is rigidly connected with the skull 2 with the portion 22 pointed outwardly from the page of FIG. 3 in a posterior direction. A second vertebra 24 is rotatably coupled with the first vertebra 18 with the cervical interspace 29 therebetween, with the portion 28 pointed outwardly from the page of the figure in a posterior direction. An opening known as a foramen magnum 14 in the skull 2 at the occipital region 4 is aligned with a corresponding opening in the vertebra known as a vertebral foramen 20 and the opening through which the spinal cord enters the back of the skull. The first vertebra 18 is also known as the “atlas” and the second vertebra 24 is also known as the “axis” in reference to their relative functions.
An inferior portion of the skull 2 is the basilar part with the basion 16 adjacent the spine and associated vertebra 18, 24. The inferior-protruding basion 16 is the mid-point on the anterior margin of the foramen magnum 14 at the base of the skull 2 where the skull articulates with the first cervical vertebra (atlas) 18. The dens 26 is a protuberance on the anterior portion of the second cervical vertebra (axis) 24. The dens 26 protrudes in a superior direction through the first cervical vertebra 18 that is connected with the skull 2, and is connected through ligaments with the basion 16 of the occipital region 4.
High-energy deceleration force often associated with motor vehicle collisions can compromise the stability provided by the strong OCC ligaments and result in spinal cord injury and death. With recent, improved pre-hospital care, the number of patients surviving such injuries and needing definitive management has increased. Some of these patients present neurologically intact, but if the OCC damage is not quickly and properly diagnosed and treated it can progress quickly and catastrophically.
FIG. 5 is a prior art bottom view (anatomical axial view) schematic showing the skull foramen magnum with an edge-wise view of sagittal plane images and their positions along the medio-lateral dimension, which images can be used to locate internal anatomical regions and features. Computerized tomography (CT) scans are commonly performed on the head of a patient transversely across the body line longitudinal axis at different depths in the X-Z plane. Then, commercially-available imaging software can reconstruct images in other planes from the original set. One type of resulting images is known as the “sagittal plane” images that are created in an orientation longitudinally along the body axis, that is, aligned in the X-Y plane of FIG. 4 and appearing as lines in FIG. 5. Thus, FIG. 5 shows the edges of sagittal-plane adjacent exemplary images 30-46 at different depths along a Z-axis. The images are used routinely in polytrauma patients and are effective at revealing cervical fractures, but may not reveal damage to soft tissues such as ligaments. Injury to the OCC ligaments can be difficult to detect. Research from those in the field, such as Dr. Christopher D. Chaput, MD in “Defining and Detecting Missed Ligamentous Injuries of the Occipitocervical Complex,” Spine, Vol. 36, No. 9, pp. 709-714 (2011), has determined that measurements of the OCC skeletal anatomy, including distances and alignments between certain skeletal landmarks, when compared with high quality normative data, can be used to detect ligamentous injury in the OCC that may otherwise be missed. However, accurately identifying the skeletal landmarks and properly interpreting the scans requires unusual care, training, and expertise.
According to the research of comparing measurements of the OCC skeletal anatomy with high quality normative data, the measurement of primary importance is the basion-dens interval (BDI), which is the linear distance from the inferior-most position of the basion to the superior-most position of the dens. If this distance exceeds a certain threshold, then the potential risk of undetected OCC injury is substantially elevated. Currently, the BDI is determined through visual inspection, usually by a physician and/or radiologist viewing a patient's CT scans or other radiologic images. The physician or radiologist manually identifies the image or images that best show the extrema points of the basion and the dens, and then uses those images to measure the BDI. Such a manual determination, however, is tedious, time-consuming, and susceptible to human error, despite the highest level of medical training, skill, and experience.
Therefore, there remains a need to provide a method and system of automatically detecting the distance between the dens and basion, and indicating automatically whether there is an elevated risk of injury.